Question First time build, saw small spark

[Skave]

So, as the title says, this is my first build and I did everything right, or so I thought. I did a post test prior to putting all the components in my case. Once I saw the post screen, I shut everything down and kept building. Once I went to turn on the PSU there was a small blue flash at the USB 3.0 port and now my cpu won't turn on. What could be the issue? Did I short my mobo? I'm not really sure.

Spec list:
B450 Aorus Elite
Ryzen 5 3600xt
16 gigs 3200 G. Skill Trident
Asrock 5600xt
Corsair RM 550x PSU

 

[rgd1101]

a short. did you use standoff?

 

[Skave]

a short. did you use standoff?

Yeah, I put the standoffs in before mobo install.